Restoration of groundwater levels

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The INOWAS plattform can be used to assess the implementation of MAR for the restoration of groundwater levels in overexploited aquifers.

Groundwater is often the main water supply source and has the advantage that the water quantity and quality is relatively constant compared to surface water from rivers and streams. Pumping from wells creates depression cones. The extent of the resulting effects depends on various factors such as pumping rate, natural discharge rates, aquifer properties (aquifer confinement, specific storage, extent) and natural or human-induced recharge rates. Overexploitation of groundwater occurs if pumping exceeds natural recharge from precipitation and surface water bodies and results in a decrease of groundwater levels. Negative effects of groundwater depletion include higher pumping costs as water needs to be lifted higher to reach the land surface. Additionally, wells can fall dry and therefore deeper drilling is necessary or wells need to be abandoned. The higher gradient can also result in a reduction of water in lakes and streams as less groundwater discharges into the surface water body or more water is recharging the groundwater depending on the local situation. Another aspect is the deterioration of groundwater quality. The higher gradient can cause higher inflow of water with lower quality (e.g. contaminants from other aquifers, rivers) as well as in coastal aquifers saltwater to migrate further inland. Land subsidence is caused by compression of aquifer material and a reduction of porosity. These changes are only partly reversible when groundwater levels later increase again and cause damages to buildings and infrastructure.

Figure 1. Mean groundwater levels from 1964-2003 for a well in Cook County, Southwest Gorgia, USA. The long-term groundwater decline caused by excessive pumping is easily visible (http://water.usgs.gov/edu/gwdepletion.html)

The INOWAS plattform can help to analyze the occurring groundwater decline and to evaluate alternative management scenarios including the implementation of MAR to restore the groundwater levels. Numerical modeling has already been widely used to evaluate the resulting groundwater levels when implementing recharge wells (Landini et al., 2006; Legg and Sagstad, 2002; Martin et al., 2012; Pyne, 2005; Sheng, 2005; Valley et al., 2006) or spreading methods such as infiltration basins (Abbo and Gev, 2008; Hashemi et al., 2014; Jorgensen and Helleberg, 2002; Namjou and Pattle, 2002; Ting et al., 2006). The groundwater flow model MODFLOW was for example used to evaluate the depleting groundwater levels in Hanoi, Vietnam (Glass et al., 2018). A GIS-based analysis helped to identify suitable locations to implement MAR. A Scenario Analysis was conducted to assess alternative management options including the implementation of injection wells and the extension of riverbank filtration to stop further groundwater level decline (Figure 2).

Figure 2. Water table difference [m] for December 2007 in a) Holocene unconfined aquifer and b) Pleistocene confined aquifer in the city centre of Hanoi, Vietnam between the base case scenario and scenario 1 riverbank filtration; scenario 2 injection wells; and scenario 3 combination of riverbank filtration and injection wells. White areas indicate cells with no head change. (Glass et al., 2018).

Example INOWAS tools that can be used to assess the restoration of groundwater levels:

  • T02.  Groundwater mounding (Hantush)
  • T03. MODFLOW model setup and editor
  • T07. MODFLOW model scenario manager

To select a suitable MAR method or a model set for the specific study area, the following tools can be used:

  • T04. Database for GIS-based suitability mapping
  • T06. MAR method selection
  • T11. MAR model selection

REFERENCES

  • Abbo, H., Gev, I., 2008. Numerical model as a predictive analysis tool for rehabilitation and conservation of the Israeli Coastal Aquifer: example of the SHAFDAN Sewage Reclamation project. Desalination 226, 47–55. doi:10.1016/j.desal.2007.01.233
  • Glass, J., Rico, D.A.V., Stefan, C., Nga, T.T.V., 2018. Simulation of the impact of managed aquifer recharge on the groundwater system in Hanoi, Vietnam. Hydrogeol J 1–16. https://doi.org/10.1007/s10040-018-1779-1
  • Hashemi, H., Berndtsson, R., Persson, M., 2014. Artificial recharge by floodwater spreading estimated by water balances and groundwater modeling. Hydrological Sciences Journal 336–350. doi:10.1080/02626667.2014.881485
  • Jorgensen, N.O., Helleberg, B.B., 2002. Stable isotopes (2H and 18O) and chloride as environmental tracers in a study of artificial recharge in Denmark, in: Dillon, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 4th International Symposium on Artificial Recharge of Groundwater. ISAR-4, Adelaide, South Australia, 22-26 September 2002. A.A. Balkema, Lisse, pp. 245–250.
  • Landini, F., Pranzini, G., Scardazzi, M.E., 2006. Evaluation of the strategies for the re-equilibrium of the groundwater balance of an overexploited aquifer (Prato, Italy), in: UNESCO (Ed.), Recharge Systems for Protecting and Enhancing Groundwater Resources – Proceedings of the 5th International Symposium on Management of Aquifer Recharge ISMAR5, Berlin, Germany, 11–16 June 2005. pp. 714–719.
  • Legg, C., Sagstad, S., 2002. Optimization and use of various recharge techniques for reclaimed wastewater at a sensitive site in Glendale, Arizona, in: Dillon, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 4th International Symposium on Artificial Recharge of Groundwater. ISAR-4, Adelaide, South Australia, 22-26 September 2002. A.A. Balkema, Lisse, pp. 333–338.
  • Martin, R., Barnett, B., Pitman, C., Kaufmann, C., Swiatnik, A., Burgess, C., 2012. Modelling the regional impacts of multiple MAR schemes on the Northern Adelaide Plains, in: Draeger, M. (Ed.), Achieving Groundwater Supply Sustainability & Reliability through Managed Aquifer Recharge – Proceedings of the Symposium ISMAR 7, 9-13 October 2009, Abu Dhabi, UAE. pp. 389–397.
  • Namjou, P., Pattle, A.D., 2002. Hydrogeological feasibility of disposal of treated effluent in coastal dunes near Auckland, New Zealand, in: Dillon, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 4th International Symposium on Artificial Recharge of Groundwater. ISAR-4, Adelaide, South Australia, 22-26 September 2002. A.A. Balkema, Lisse, pp. 273–277.
  • Pyne, R.D.G., 2005. Aquifer storage recovery: a guide to groundwater recharge through wells. ASR Systems, Gainesville, Florida.
  • Sheng, Z., 2005. An aquifer storage and recovery system with reclaimed wastewater to preserve native groundwater resources in El Paso, Texas. Journal of Environmental Management 75, 367–377. doi:10.1016/j.jenvman.2004.10.007
  • Ting, C.-S., Lee, C.H., Lin, C.Y., Chen, S.H., Chang, K.C., 2006. Infiltration mechanism of artificial recharge of groundwater – A case study at Pingtung Plain, Taiwan, in: UNESCO (Ed.), Recharge Systems for Protecting and Enhancing Groundwater Resources – Proceedings of the 5th International Symposium on Management of Aquifer Recharge ISMAR5, Berlin, Germany, 11–16 June 2005. pp. 747–754.
  • Valley, S., Landini, F., Pranzini, G., Puppini, U., Scardazzi, M.E., Streetly, M.J., 2006. Transient flow modelling of an overexploited aquifer and simulation of artificial recharge measures, in: UNESCO (Ed.), Recharge Systems for Protecting and Enhancing Groundwater Resources – Proceedings of the 5th International Symposium on Management of Aquifer Recharge ISMAR5, Berlin, Germany, 11–16 June 2005. pp. 435–442.